Steam surface condenser



Oct. 25, 1966 Filed Sept. 2, 1964 K. WARTENBERG STEAM SURFACE CONDENSER 4 Sheets-Sheet l Fig.1 9

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Filed Sept. 2, 1964 4 Sheets-Sheet 2 Fig.3

Oct. 25, 1966 K. WARTENBERG STEAM SURFACE CONDENSER 4 Sheets-Sheet 3 Filed Sept. 2, 1964 Oct. 25, 1966 K. WARTENBERG 3,280,900

STEAM SURFACE CONDENSER Filed Sept. 2, 1964 4 Sheets-Sheet 4 Jnvenlor:

United States Patent 3,280,900 STEAM SURFACE CONDENSER Kurt Wartenberg, Kemmansweg 14, Kettwig (Ruhr), Germany Filed Sept. 2, 1964, Ser. No. 394,001 laims priority, application Austria, Sept. 6, 1963, A 7,181; Sept. 16, 1963, A 7,402; Feb. 3, 1964, A 818 11 Claims. (Cl. 165122) The present invention relates to an air-cooled heattransfer device. More specifically, this invention is concerned with an air-cooled steam surface condenser that is used as part of a steam power plant cycle and wherein the steam-condensate passages as Well as the cooling-air passages are designed and arranged in such a manner that a reliable and advantageous operation of the condenser is insured.

Air is the gas most commonly used as cooling medium, and it has the advantage that it is anywhere and at any time available.

However, certain points have to be observed when air is employed as heat-receiving medium in a condenser system. Thus, air has a relatively low heat capacity which, in conjunction with its relatively poor heat-transfer properties, requires large heat-transfer surfaces when air is used for cooling purposes. As a result, condenser systems of the air-cooled type are of relatively large dimensions. in addition to large heat-transfer surfaces, an aircooled heat transfer device requires that the cross-sections of the air passages be relatively large, to insure an efiicient heat transfer. On the other hand, the air-flow path through the heat-transfer elements should be as short as possible to keep the amount of power required to draw air through the heat-transfer elements within tolerable limits.

Consideration must also be given to the fact that air, when used as cooling agent, may assume temperatures down to far below the freezing point. Therefore, special measures have to be taken to prevent an undesired loss of heat by subcooling. In particular, provision must be made to prevent the formation of ice on the steam side of the cooling surface of the heat-transfer elements, since ice would tend to destroy the condenser completely.

There are two arrangements for the steam-condensate flow through a condenser system, viz., parallel flow and counter flow.

In the first arrangement (parallel flow), steam and condensate flow essentially in the same direction to that portion of the steam condensing zone where the pressure is at a minimum. That is to say, they flow to the condensate storage tank and the collection point for the nonc-ondensable gases, which are then removed by suitable means.

In the second arrangement (counter flow), the condensate and the steam flow essentially in opposite directions. That is to say, the condensate flows to a zone where the pressure is at a maximum, whereas the noncon-densable gases of the steam to be condensed are directed to a zone where the pressure is at a minimum and removed there.

The first arrangement has the advantage that no large amounts of materials are required for the construction of the condenser system, because the permissible steam velocities may be as high as 230 to 260 feet per second so that the cross-section of the steam zone may be made relatively small which, in turn, permits the overall dimensions of the condenser system to be made relatively small also.

On the other hand, such an arrangement has the disadvantage that under partial load conditions or. when the ice temperature of the cooling air has fallen below the design temperature, the condensate may become subcooled.

Should the temperature of the outside air fall below the freezing point, ice may form on the steam side of the heattransfer elements, thereby exposing the equipment to the danger of being destroyed. This danger is particularly imminent, if the condenser is operated under partial load conditions or the cooling-air temperatures are very low, since in such a case the condensing process would be [terminated before the steam would have flowed through the entire condensing section, because steam and condensate would flow in the same direction to minimum pressure zones. In such a case the condensate obtained would still remain exposed to the full cooling effect of the air in those portions of the heat-transfer system that had not yet been traversed by the condensate. Hence, the condensate would become cooled down to the critical temperature limit.

'It is true that the second, counter-flow, arrangement is not exposed to such a danger. However, arrangements of this kind that have heretofore been employed have had the disadvantage that they require much space in addition to large amounts of material. These disadvantages result from the low steam velocities which in no case are allowed to exceed 65 feet per second. Otherwise, the condensate reflux might be disturbed whereby the condensate would be caused to foam up or form bubbles and so-called steam blows may occur whose detrimental eifects are well known to those skilled in the art.

Relatively large steam passage cross-sections are characteristic of relatively low steam velocities. However, such large cross-sections are necessary only at the steam inlet side of the heat-transfer elements, since the steam is quickly reduced in volume because of the progressive eondensation,-s-o that finally its volume is not greater than five to eight percent of the original steam volume. This remaining steam volume consists essentially of noncondensable gases which are present, almost without exception, in any condenser. However, such non-condensable gases are saturated with steam so that they have to be cooled to about 5 to 9 F. below the condensing tempera- .ture to permit them to be removed as unsaturated gases by suitable means from the steam section of the condenser system.

In the past, various suggestions have been made to eliminate the disadvantages inherent in the two aforedescribed types of steam-and-condensate flow in aircooled condenser systems. Thus, it has been suggested to arrange externally finned tubes or cooling elements in such a manner that part of the heat-transfer device is used for parallel flow of steam and condensate, While through another part of the device steam and condensate flow in opposite directions. These suggestions, however, have not proved successful, because they require the installation of complex control facilities which themselves may give rise to numerous troubles in operation.

It is accordingly a primary object of this invention to provide a heat-transfer device which employs air as cooling medium and in which the disadvantages heretofore encountered in air-cooled heat-transfer devices are eliminated.

Another object of the invention is to provide an aircooled surface condenser in which provision is made to prevent excessive cooling of the condensate and formation of ice.

Yet another object of the invention is to provide a steam surface condenser of the air-cooled type wherein the amount of material required is kept within tolerable limits.

Still another object of the invention is to provide a steam condenser wherein the steam passages are dimensioned in accordance with the progressive decrease in volume of the steam.

Another object of the invention is to provide an aircooled steam condenser that can be economically constructed.

A further object of the invention is to provide a heatrtransfer device in which the advantages inherent in steamcondensate circuits of the paralleland counter-flow types are utilized.

Another object of the invention is to design the heattransfer elements of an air-cooled steam surface condenser in such a manner that they may be prefabricated and assembled to heat-transfer units.

According to one feature of the invention, bafile platesare arranged within the steam-condensate passages whereby condensing and subcooling zones are established, the former being gradually reduced in cross-section in accordance with the progressive decrease in volume of the steam passing therethr-ough.

According to another feature, the advantages of a counter-flow arrangement wherein steam and condensate flow in opposite directions are utilized by progressively reducing the steam passages in cross-section in such a manner that at the end of the steam-flow path the crosssection of the passages is not greater than eight to ten percent of the cross-sectional area of the steam passages at the steam inlet side.

According .to another feature of the invention, the subcooling zones both in parallel-flow and counter-flow arrangements of steam-condensate circuits as well as in combinations of both are formed by strip-shaped condensate collection trays or plates which are arranged in such a manner .that the subcooling zones are established in proximity to the air inlet side.

In accordance with another feature, the baffle plates and condensate collection trays are disposed in such a manner that gravitational forces are sufficient to cause the condensate to flow to the condensate storage tanks.

According 'to a further feature, the above-described bubbling of the condensate in steam circuits in which steam and condensate flow in opposite directions is positively prevented by sealing oif the lower portions of the steam inlet cross-section of the steam passages by seal baflles which, in conjunction with subcooling zone sealing means, define a passage through which the condensate flows to the condensate storage tank.

According to another embodiment of the invention, the baflle plates are arranged in such manner within the steam passages that the condensing section is subdivided into first and second condensing zones, the arrangement being such that in the first condensing zone a substantially parallel How of steam and condense is effected, whereas in the second condensing zone steam and condensate generally flow in opposite directions.

Further features and advantages of the invention will become apparent from the following description, when read in conjunction with'the appended drawings, in which several embodiments are shown.

In the drawings.

FIGURE 1 is a section of the condenser of the inventoon taken along line II--II in FIG. 2;

FIGURE 2 isa partial section and a detail view of the condenser of FIG. 1 taken along line II of FIG. 1;

FIGURE 3 is a detail of a portion of another embodiment of a condenser constructed in accordance with the invention;

FIGURE 4 is a detail of a portion of a further embodiment of a condenser constructed in accordance with the invention;

FIGURE 5 is a side elevation of a portion of a condensing section;

FIGURE 6 is a top plan view of two parallel, spaced rows of heat-transfer elements serving as cooling-air channels, the arrangement being such that steam-condensate passages are established between adjacent rows of cooling-air channels;

FIGURE 7 is an end view of the arrangement of FIG. 6 as seen from the steam inlet side, and

FIGURE 8 is an embodiment of a heat-transfer element of the invention.

Referring now more particularly to the drawings, there is shown a horizontal steam-supply pipe 1 in FIG. 1, which is in communication with a riser 3 through pipe connecting means 2. Riser 3 extends through a condensate storage tank 5 that is located uncovered beneath a steam distribution chamber 4. lanes-as well as the air lanes to be described hereinafter are accommodated in a box-shaped structure having side walls '6 and being enclosed by a shell 8.

A supporting framework 7 carries the structures at the top of which a dome 9 is arranged which accommodates a gear unit 10 including a motor for driving an exhaust fan 1. A diffuser 12 communicates with the outlet of fan 11. Fan 11 draws cooling air through the condenser system as indicated by flow lines 13. The steam is condensed in the box-shaped structure enclosed by side walls 6. In the embodiment shown, this structure is also closed at the top and bottom by end plates 14 and 14' respectively, with air lanes 15 extending therethro-ugh. In the embodiment of FIG. 1 and 2 air passages 15' are established by rows of successive, internally finned tubes or heat-transfer elements 15, through which cooling air is directed. As shown in greater detail in FIGS. 5 through 8, elements 15 have a substantially rectangular cross-section. Steam-condensate passages 16 are defined 'by arranging the rows of successive cooling elements I15 in parallel, spaced relationship, with passages 16 being in communication with steam distribution chamber 4 at the steam inlet side.

Bafile plates 17 are arranged within steam-condensate passages 16 thereby establishing upper and lower condensing zones. Baflle plates 17 are inclined with respect to the horizontal in such a manner that the steam passages are progressively reduced in cross-section in accordance with the progressive decrease in volume of steam at certain steam velocities. The upper passage portions or condensing zones lead into a chamber 18 which is disposed above steam distribution chamber 4 and is in communication with subcooling zones 20 through pipe means 19. Strip-shaped condensate collection trays 21 are provided to separate the lower steam passage portions from subcooling zones 20 which communicate with condensate storage tank 5 at their one end and with a space 22 between side walls 6 and shell 8 at their other end.

In addition, subcooling zones 20 are sealed off against steam distribution chamber 4 by seal baffles 23- which are immersed in the condensate fluid. Gases in space 22 are removed by suitable means, not shown, through gas outlets 24.

In a condenser system of the invention, the condensing process is as follows:

The exhaust steam of a power engine is fed through steam-supply pipe 1 and pipe connecting means 2 to riser 3, whence it enters steam distribution chamber 4. The steam is then admitted to steam-condensate passages 16 which are subdivided into upper and lower condensing zones by bafile plates 17, with the lower condensing zones being separated tfrom the subcooling zones 20 by stripshaped condensate collection trays 21. The steam-flow path through the steam condensing zones is determined by baflle plates 17 which, because of their inclined arran-gement, are effective to gradually reduce the steamflow path in area in accordance with the progressive decrease in volume of the steam in such a manner that at the place where the yet steam-saturated non-condensable gases leave steam-condensate passages 16 the cross section of the steam-flow path is about one-twelfth to The steam-condensate one-tenth the size of the cross-sectional area of the steamflow path at the inlet side.

The condensate running down the walls of heat-transfer elements flows over sealing baffles 23 to condensate storage tank 5, the flow being enhanced and directed by the inclined arrangement or by the geometry of collection trays 21. A condensate drain pipe 25 returns the condensate to the feed system, not shown, for re-use as feed-water. The noncondensable gases accumulate in chamber 18 above steam distribution chamber 4 and are directed through pipes 19 to subcooling zones 20 which :are located at the air inlet side of the condenser, that is, at the cold-air side. In subcooling zones 20 the noncondensable gases which are still saturated with steam are then cooled to about 9 F. below the saturated steam temperature corresponding to pressure, thereby allowing the greater amount of steam entrained to condense also. The condensate dripping from heat-transfer elements 15 into subcoolin-g zones 20 is also directed to condensate storage tank 5, entering tank 5 at the lower side of seal baffles 23. The dry gases are directed to space 22 where they are removed through gas outlets 24 by suitable means not shown.

As previously stated, exhaust fan 11 operates to draw the cooling air upwards through passages 15. This air circuit has the advantage that, when used in conjunction with the condenser of the invention, any effect of the ever varying atmospheric conditions, such as wind influence and solar radiation, on the efficiency of the aircontacter cooling surfaces will be eliminated. In other words, with the ambient temperature given, the efficiency of the heat-transfer surface is determined solely by the quantity of air delivered by exhaust fan 11 or by the air velocity in the air passages. It should be understood that exhaust fan 11 has means for varying its speed.

The embodiment shown in FIG. 3 is substantially similar to that of FIGS. 1 and 2, except for a few minor modifications. In FIG. 3, parts corresponding to those shown in FIGS. 1 and 2 are provided with similar numerals followed by a superscript The major difference between the two embodiments of FIGS. 1 and 3 consists in that in the embodiment of FIG. 3 the inclined arrangement of condensate collection trays 21' is reversed with respect to the arrangement of FIG. 1. In this manner, a parallel flow of steam and condensate is achieved in condensing zone 26, whereas in the following condensing zone 27 steam and condensate flow essentially in opposite directions. Due to the inclination of condensate collection trays 21' and balfie plates 17 the condensate accumulating thereon flows to the right-hand side of the condenser portion shown in detail in FIG. 3, where it enters an auxiliary condensate storage tank 5" which is in communication with condensate storage tank 5' through suitable connecting pipes 28.

The flow paths of the steam and condensate as controlled by baffie plates 17 and condensate collection trays 21 are indicated by arrows in FIG. 3. As shown in this figure, the steam-flow path is gradually reduced in area between steam inlet 29 and area 30 where steam flow is reversed, the reduction corresponding to the progressive decrease in volume of steam as the condensation proceeds. In the parallel-flow zone 26 in which steam and condensate generally flow in the same direction, the steam velocity or variations in steam velocity have no disadvantageous effect on the operation of the condenser. At 31, where the condensing steam enters zone 27 the cross-section of the steam-flow path is substantially equal to that at steam inlet 29. However, the permissible steam velocity in this circuit arrangement will not be exceeded at any place, although the size of steam inlet 29 was selected for higher steam velocities. This is so, because only about one-fifth to one-third of the total quantity of steam will enter the counter-flow zone 27 at its entry end 31.

As has already been previously stated, it is the tail section of the overall steam-flow path that constitutes the critical zone in which excessive cooling or formation of ice has to be expected, before the condensate leaves the heat-transfer system. To eliminate this danger, in the embodiment of FIG. 3, the critical zone 27 is located above baffie plates 17', at the same time making provision for the steam and condensate to flow in opposite directions.

In FIG. 4, another embodiment is shown in which provision is made to prevent the condensate from bubbling or foaming. In this figure, a portion of the condenser similar to that of FIG. 3 is shown. Hence, no description is given here of the details in which the two portions are identical. In this embodiment there is no possibility for the condensate reflux to foam or bubble, and, consequently, no steam blows will occur.

It is true that the detrimental effects of bubbling and steam blows may be considerably reduced, as in the case of the embodiments previously described, by dirnensioning the cross-section of the steam-condensate passages at the steam inlet side in such a manner that steam velocities over 65 feet per second are impossible. As regards the steam velocity at the steam inlet, it should be noted, however, that the velocity should preferably be uniform across the entire cross-sectional area of the inlet. However, experience has shown that in the case of cross-flow arrangements, in which the two heatexchanging media, steam and air, flow at substantially right angles, consideration must be given to the effect of the temperature gradient between the saturated steam temperature at the inlet and the temperature of cooling air flowing through the vertically disposed tubes or cooling elements on the steam velocity in the inlet crosssection. Since the magnitude of the temperature gradient determines the difference in pressure and, consequently, the steam velocity, it is obvious that the steam velocity will be at a maximum at the cooling-air inlet side, that is, at that place at the steam-inlet where the condensate flowing to the condensate storage tank leaves the steam-condensate passages. Therefore, in such a case it is possible that the leaving condensate would tend to bubble or foam up, even if the cross-section of the steam inlet had been dimensioned so as to obtain a mean steam velocity of 65 feet per second.

According to the invention, this disadvantage is avoided by sealing the lower portions of the inlet cross-sections of the steam-condensate passages against steam dis-tribution chamber 4' by seal baffles 32 which, in conjunction with seal baffles 23, define a passage through which the condensate flows to condensate storage tank 5'. Seal baffies 32 are effective to deflect the steam entering the steam-condensing passages in such a manner that part of the steams flow in vertical direction whereby the condensing of steam on the cooling surfaces is accelerated, at the same time insuring that the steam velocity immediately above the condensate stream is virtually zero, so that there is no possibility anymore for the condensate to foam up or form bubbles.

All the embodiments described hereinbefore, can be constructed from heat-transfer elements shown in FIGS. 5 through 8.

While the novel features of the invention as applied to preferred embodiments have been shown and described herein, it will be obvious that modifications of the heat-transfer device shown may be made without departing from the spirit and the scope of the invention. Accordingly, the scope of this invention is to be governed by the language of the following claims construed in the light of the foregoing description of this invention.

It is claimed and desired to secure by Letters Patent:

1. In an air-cooled steam surface condenser for condensing exhaust steam from a steam power engine, heattransfer elements arranged in parallel rows and adjacent rows of said heat-transfer elements defining steam-condensate passage therebetween, variable fan means for drawing a cooling gas through said heat-transfer elements, dividing means disposed in said steam-condensate passages to establish upper and lower condensing zones therein separated by the dividing means, said dividing means being inclined with respect to the horizontal to gradually reduce said steam-condensate passages in crosssection in accordance with the progressive decrease in volume of steam passing therethrough, steam-condensate subcooling zones in communication with the upper condensing zone, separating means disposed in said steamcondensate passages for separating said lower condensing zone from the subcooling zones, condensate storage means, and a steam distribution chamber, said lower condensing zone receiving the exhaust steam at a steam inlet side from said steam distribution chamber and the steam passing from the lower to the upper zone, and the steamcondensate passages being in communication with said condensate storage means.

2. A condenser according to claim 1 in which the steam-flow path cross-section reduction is such that at the place where the steam leaves said lower condensing zone the sectional area of said lower condensing zone is not greater than about one-twelfth of the sectional area of said steam-flow path at the steam inlet side thereof.

3. A condenser as in claim 1 in which said dividing means are arranged in such a manner that parallel flow of steam and condensate is achieved in said lower condensing zone, whereas in said upper condensing zone steam and condensate flow substantially in opposite directions.

4. The condenser according to claim 3 in which the lower condensing zone is in communication with the upper condensing zone, pipe means connects the upper condensing zone with the subcooling zones to remove noncondensable gases therefrom, and gas outlet means is connected to said subcooling zones.

5. In an air-cooled steam surface condenser for condensing exhaust steam from a steam power engine, heattransfer elements arranged in parallel rows and adjacent rows of said heat-transfer elements defining steam-condensate passages therebetween, variable fan means for drawing a cooling gas through said heat-transfer elements, dividing plates disposed in said steam-condensate passages to establish lower and upper condensing zones therein separated by the dividing plates, said dividing plates being inclined with respect to the horizontal to gradually reduce said steam-condensate passages in cross-section in accordance with the progressive decrease in volume of steam passing therethrough, the reduction being such that at the place where the steam leaves said lower condensing zone the cross-sectional area of said lower condensing zone is not greater than about one-twelfth of the sectional area of said lower condensing zone at a steam inlet side thereof, steam-condensate subcooling zones in communication with the upper condensing zone, separating means disposed in said steam-condensate passages for separating said lower condensing zone from the subcooling zones, condensate storage means, a steam distribution chamber, said lower condensing zone receiving the exhaust steam at the steam inlet from said steam distribution chamber and the steam passing from the lower to the upper zone, and the steamcondensate passages being in communication with said condensate storage means, said subcooling zones being located at the cooling gas inlet side and sealing means separating said steam distribution chamber from the subcooling zones.

6. A condenser according to claim 5 in which the dividing plates and separating means are inclined in such a manner that gravitational forces are sufficient to cause the condensate to flow to the condensate storage means.

'7. A condenser according to claim 5 in which seal bafiles are provided to seal off the lower portions of the inlet cross-sections of the steam-condensate passages against the steam distribution chamber, said seal bafiles in cooperation with the sealing means defining a passage through which the condensate flows to said condensate storage means.

8. In a steam surface condenser, heat-transfer elements arranged in parallel rows and adjacent rows of said heattransfer elements defining steam-condensate passages therebetween, variable fan means for drawing cooling gas through said heat-transfer elements, dividing plates disposed in said steam-condensate passages to establish lower and upper cooling zones therein separated by said dividing plates, said dividing plates being inclined with respect to the horizontal to gradually reduce said steam-condensate passages in cross-section in accordance with the progressive decrease in volume of steam passing therethrough, steam-condensate subcooling zones in communication with the upper condensing zone, separating means disposed in said steam-condensate passages for separating said lower condensing zone from the subcooling zones, a condensate storage tank, a steam distribution chamber, riser means, said lower condensing zone receiving steam from said steam distribution chamber and the steam passing from the lower to the upper zone, and the steam-condensate passages being in communication with said condensate storage means, said riser means communicating with said steam distribution chamber, and seal baffles sealing the outlets of said subcooling zones against the condensate leaving the condensing zones, said seal baflles extending into said condensate storage tank and forming a fluid seal with the condensate in said storage tank.

9. A condenser according to claim 8 in which the heattransfer elements are rectangular, internally finned tube members which, when assembled, define the steam-condensate passages.

10. A condenser according to claim 9 including side walls, a shell, and a framework, said side walls and said shell enclosing the heat-transfer elements and forming a box-shaped structure, said structure being supported by the framework and the riser means.

11. A condenser according to claim 8 in which said gas is air.

References Cited by the Examiner UNITED STATES PATENTS 1,159,775 11/1915 Kerr -111 1,406,356 2/1922 Ehrhart 165114 1,845,546 2/1932 Smith 165114 3,204,693 9/1965 Kuhn 165111 ROBERT A. OLEARY, Primary Examiner.

A, ANTONAKAS, Assistant Examiner. 

1. IN AN AIR-COOLED STEAM SURFACE CONDENSER FOR CONDENSING EXHAUST STEAM FROM A STEAM POWER ENGINE, HEATTRANSFER ELEMENTS ARRANGED IN PARALLEL ROWS, AND ADJACENT ROWS OF SAID HEAT-TRANSFER ELEMENTS DEFINING STEAM-CONDENSATE PASSAGE BETWEEN, VARIABLE FAN MEANS FOR DRAWING A COOLING GAS THROUGH SAID HEAT-TRANSFER ELEMENTS, DIVIDING MEANS DISPOSED IN SAID STEAM-CONDENSATE PASSAGES TO ESTABLISH UPPER AND LOWER CONDENSING ZONES THEREIN SEPARATED BY THE DIVIDING MEANS, SAID DIVIDING MEANS BEING INCLINED WITH RESPECT TO THE HORIZONTAL TO GRADUALLY REDUCE SAID STEAM-CONDENSATE PASSAGES IN CROSSSECTION IN ACCORDANCE WITH THE PROGRESSIVE DECREASE IN VOLUME OF STEAM PASSING THERETHROUGH, STEAM-CONDENSATE SUBCOOLING ZONES IN COMMUNICATION WITH THE UPPER CONDENSING ZONE, SEPARATING MEANS DISPOISED IN SAID STEAMCONDENSATE PASSAGES FOR SEPARATING SAID LOWER CONDENSING ZONE FROM THE SUBCOOLING ZONES, CONDENSATE STORAGE MEANS, AND A STEAM DISTRIBUTION CHAMBER, SAID LOWER CONDENSING ZONE RECEIVING THE EXHAUST STEAM AT A STEAM INLET SIDE FORM SAID STEAM DISTRIBUTION CHAMBER AND THE STEAM PASSING FROM THE LOWER TO THE UPPER ZONE, AND THE STEAMCONDENSATE PASSAGE BEING IN COMMUNIATION WITH SAID CONDENSATE STORAGE MEANS. 